#ifdef DEBUG
#include "pch.hpp"
#else
#include <bits/stdc++.h>
#if __has_include(<atcoder/all>)
#include <atcoder/all>
#endif
#endif
// #include <boost/multiprecision/cpp_int.hpp>
using namespace std;
using std::cerr, std::cin, std::cout;
#define vec vector
#if __has_include(<atcoder/all>)
using mint = atcoder::modint998244353;
std::istream &operator>>(std::istream &is, mint &a) {
	long long t;
	is >> t;
	a = t;
	return is;
}
std::ostream &operator<<(std::ostream &os, mint a) { return os << a.val(); }
vec<mint> operator*(const vec<mint> &a, const vec<mint> &b) { return a.empty() || b.empty() ? vec<mint>() : atcoder::convolution(a, b); }
vec<mint> &operator*=(vec<mint> &a, const vec<mint> &b) { return a = a * b; }
#endif
typedef long double ld;
#define long long long
#define uint unsigned int
#define ulong unsigned long
#define overload3(a, b, c, name, ...) name
#define rep3(i, a, b) for (int i = (a); i < (b); i++)
#define rep2(i, n) rep3(i, 0, n)
#define rep1(n) rep2(__i, n)
#define rep(...) overload3(__VA_ARGS__, rep3, rep2, rep1)(__VA_ARGS__)
#define per3(i, a, b) for (int i = (b) - 1; i >= (a); i--)
#define per2(i, n) per3(i, 0, n)
#define per1(n) per2(__i, n)
#define per(...) overload3(__VA_ARGS__, per3, per2, per1)(__VA_ARGS__)
#define all(a) a.begin(), a.end()
#define UNIQUE(a) sort(all(a)), a.erase(unique(all(a)), a.end()), a.shrink_to_fit()
#define sz(a) static_cast<int>(a.size())
#ifndef DEBUG
#define cerr \
	if (0) cerr
// #undef assert
// #define assert(...) void(0)
#undef endl
#define endl '\n'
#endif
template <typename T>
ostream &operator<<(ostream &os, vector<T> a) {
	const int n = a.size();
	rep(i, n) {
		os << a[i];
		if (i + 1 != n) os << " ";
	}
	return os;
}
template <typename T, typename S>
istream &operator>>(istream &is, pair<T, S> &a) {
	return is >> a.first >> a.second;
}
template <typename T, typename S>
ostream &operator<<(ostream &os, pair<T, S> a) {
	return os << a.first << ' ' << a.second;
};
template <typename T, size_t n>
ostream &operator<<(ostream &os, array<T, n> a) {
	rep(i, n) {
		os << a[i];
		if (i + 1 != n) os << " ";
	}
	return os;
}
template <typename T>
istream &operator>>(istream &is, vector<T> &a) {
	for (T &i : a) is >> i;
	return is;
}
template <typename T, typename S>
bool chmin(T &x, S y) {
	if ((T)y < x) {
		x = (T)y;
		return true;
	}
	return false;
}
template <typename T, typename S>
bool chmax(T &x, S y) {
	if (x < (T)y) {
		x = (T)y;
		return true;
	}
	return false;
}
template <typename T>
void operator++(vector<T> &a) {
	for (T &i : a) ++i;
}
template <typename T>
void operator--(vector<T> &a) {
	for (T &i : a) --i;
}
template <typename T>
void operator++(vector<T> &a, int) {
	for (T &i : a) i++;
}
template <typename T>
void operator--(vector<T> &a, int) {
	for (T &i : a) i--;
}
vec<long> fa(long n) {
	vec<long> yakn;
	long p = 1;
	for (; p * p < n; p++) {
		if (n % p == 0) {
			yakn.push_back(p);
			yakn.push_back(n / p);
		}
	}
	if (p * p == n) yakn.push_back(p);
	sort(all(yakn));
	return yakn;
}
void solve() {
	int n, m;
	long a, b;
	cin >> n >> m >> a >> b;
	vec<long> c(m);
	cin >> c;
	unordered_map<long, vec<long>> yak;
	{
		auto yakn = fa(n);
		for (long d : yakn) yak[d] = fa(d);
	}
	constexpr long INF = 1e18;
	unordered_map<long, long> d;
	auto f = [&](auto f, long n) -> long {
		if (n == 1) return 0;
		if (d.contains(n)) return d[n];
		long ans = INF;
		for (long k : yak[n]) {
			if (k == n) continue;
			bool ok = true;
			for (long cc : c)
				if (cc % k == 0 && k <= cc && cc <= n) ok = false;
			if (!ok) continue;
			chmin(ans, b + (n / k - 1) * a + f(f, k));
		}
		return d[n] = ans;
	};
	long ans = f(f, n);
	cout << (ans == INF ? -1 : ans - b) << endl;
}
int main() {
	// srand((unsigned)time(NULL));
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	cout << fixed << setprecision(20);
	int t = 1;
	// cin >> t;
	while (t--)
		solve();
}